This post originally ran in April 2013. We are rerunning it with Jurassic World opening this weekend.

"If people knew where the sounds in Jurassic Park came from, it'd be rated R!" laughed Gary Rydstrom. The sound designer rang me up last week to discuss his work on the Steven Spielberg action classic, newly rereleased in 3-D; when the movie came out in 1993, it netted him two Academy Awards for sound design and mixing (he's been nominated an astonishing 17 times over his career, winning seven statuettes). Though the Jurassic job was fun, Rydstrom remembers it as a tall order: He had to create dozens of distinct dinosaur noises essentially from scratch, since no one really knows what these long-dead animals would have sounded like. His solution was to spend months recording animal noises — some exotic, some not — then tweaking those homegrown sounds to create something otherworldly but still organic. What recognizable animals did he use to mix together the raptor, the T. rex, and all of Jurassic Park's other dinosaurs? Read on, if you dare: As Rydstrom implied, some of the sounds are sorta smutty.

VelociraptorsThe intelligent raptors appear to have their own simple language, and it turns out that it's the language of love. "It's somewhat embarrassing, but when the raptors bark at each other to communicate, it's a tortoise having sex," said Rydstrom. "It's a mating tortoise! I recorded that at Marine World … the people there said, 'Would you like to record these two tortoises that are mating?' It sounded like a joke, because tortoises mating can take a long time. You've got to have plenty of time to sit around and watch and record them."

Still, that wasn't the only animal element used to create the raptor noises. "When the raptor shows up in the door window in the kitchen, the breathing noise is a horse," said Rydstrom. "We used the horse in about three to four different dinosaurs." What about the hiss that raptor makes when it ambushes the game warden Muldoon (which prompts him to mutter, "Clever girl")? "That’s a goose. Birds make pretty raspy sounds, but geese are famous for being the nastiest. You’ve got to get a goose mad and then they hiss at you, and it doesn't take much to get a goose mad because they seem to get mad at everything. All you have to do is get close to one and stick a mic near its beak and you'll get that hiss, and that's the hiss that Muldoon hears before he dies."

Gallimimus If the Gallimimus flock recalls a stampede of wild horses, there's good reason for it. "I remember recording a female horse, and the male horse came right by her and she squealed because she was in heat," laughed Rydstrom. "A lot of animals in heat make a very unique sound, and she squealed at this male because he got a little too close and she was excited about the male, I assume. And that’s the squeal the Gallimimuses make when they’re passing by, and the squeal one makes when it's getting eaten by a T. rex. One of the key elements of the raptor screams was a boy dolphin in heat, so you can see a pattern here!"

Tyrannosaurus rexThe fearsome Tyrannosaurus rex is one of the biggest animals in Jurassic Park, but some of its key noises came from Rydstrom's tiny Jack Russell terrier, Buster. "The way they animated the T. rex was very doglike, especially when it grabs the Gallimimus and the lawyer and shakes them to death," said Rydstrom. "Every day I would see my dog playing with the rope toy and doing exactly that, pretending like he's killing his prey." Was Buster's Jurassic Park cameo an isolated incident? "No, I use my pets all the time," laughed Rydstrom. "In Terminator 2, I recorded the sound of Buster eating puppy chow, and that became the crunch when the T-1000 spiked that guy’s eye socket."

"One of the fun things in sound design is to take a sound and slow it down: It becomes much bigger," he continued. "That was inspired by Ben Burtt, the great sound designer from the Star Wars movies and a mentor of mine: He did the Rancor beast in Return of the Jedi by slowing a chihuahua sound down. It's one of the secrets of sound design that if you slow something down, something small, it brings out elements of the sound that you could probably never get if you recorded something big."

As for that bone-shivering, theater-shaking T. rex roar: "The key element of the T. rex roar is not a full-grown elephant but a baby elephant," said Rydstrom. "So once again, a small animal making a small sound slowed down a little bit has more interest to us than what a big animal might do."

Brachiosaurus"The brachiosaur’s singing is one of my favorite sounds in the movie because it’s beautiful, but like all good sound design, it's made from a non-beautiful source, which is donkeys," said Rydstrom. "You think of donkeys, and they kind of yodel, you know? There's this pitch shift in donkey vocals, and if you slow them way down, you get almost a hooting, songlike quality. That's the brachiosaur when it’s in its splendor mode." And what about later in the movie, when it's in its sneezing mode? "That's a whale blowhole and a fire hydrant."

Triceratops"I work at Skywalker Ranch, which has a lot of cattle around, so I used a lot of cows for the triceratops," said Rydstrom. "But the main sound of the sick triceratops is its breathing — this long, slow inhale and exhale — and that's actually one of the only elements of the movie that isn't an organic sound. I used this long cardboard tube with a spring in it, a reverb device that makes sounds seem stretched out and deeper and weird. So when Sam Neill puts his ear right up to the chest cavity of the triceratops and listens to its breathing, there's a lot of cow in there, but the key element of the breathing is mostly me breathing into a tube."

Rydstrom admitted that he did sneak one other human voice into the movie: his friend Dietrich. "He was visiting me and I turned on the mic and said, 'Can you make any weird sounds?' And he did this phlegmy, guttural growl. In the kitchen attack scene, there’s a close-up of the raptor slowly opening its mouth when it's about to attack Lex as she's hiding in a cabinet, and that sound is mostly my friend Dietrich doing this weird guttural growl. At the time, it felt like cheating when I would use myself or any other human to make a dinosaur sound — I felt like I was cheating the sound-design gods!"

Baby RaptorThe sounds Rydstrom used to animate the newly hatched dinosaur are just as adorable as the creature itself. "It's just been born, so at first it’s really squeaky and cute, and we recorded a lot of baby animals: baby owls, baby foxes, and things like that," he said. And no, your ears aren't deceiving you: When Sam Neill finds out that the cute baby dino is actually a vicious velociraptor, the sounds it emits become more … unsettling. "That's exactly right; as soon as he asks, 'What kind of dinosaur is this?' you start hearing these raspier baby owl sounds," said Rydstrom. "I already knew what the adult raptor would sound like, that it would have this screechy, raspy sound, so I tried to find a baby animal that has that rasp in it."

DilophosaurusWhen we first meet the Dilophosaurus, it cocks its head at Dennis Nedry and lets out an appealing trill. "Made from a swan," revealed Rydstrom. "Swans make a cute hooting sound, so the cute version of the Dilophosaurus sounds like a swan, for the most part." He chuckled. "Part of the fun of doing these kind of jobs is that I had no idea what a swan sounded like before!"

Of course, things quickly escalate with the Dilophosaurus as it grows a fearsome cowl and expectorates all over its prey. "When it's the scary spitter, there’s definitely a rattlesnake sound in there as it fans out its canopy around its head, and the raspy sounds in its voice are from a hawk," said Rydstrom, adding with a laugh, "Whenever I give lectures to people about getting sounds for movies, one of the key things I tell them is that when you’re recording dangerous animals like lions and alligators and rattlesnakes, then you have your assistant do it! On Jurassic Park, I had an assistant, the lovely Chris Boyd — who's still alive — and if we needed a rattlesnake, I’d say, 'Chris, please record the rattlesnake.' And I’d record the dogs and the kittens!"

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